Reading Disabilities (RD) and Attention Deficit/Hyperactivity Disorder (ADHD) are common neurodevelopmental disorders with evidence for shared genetic etiology. This study examined four predicted neuronal migration genes in RD (DCDC2, KIAA0319, DCDC2B and NEDD4L), and three of these genes in ADHD (DCDC2, DCDC2B and NEDD4L).
Putative regulatory elements of DCDC2 (6p) and KIAA0319 (6p) were screened to identify functional risk variants that explain previous association findings. No statistically significant associations were observed in DCDC2. In KIAA0319, variants with predicted regulatory function showed association with RD. This supports the hypothesis that causal RD risk variants in KIAA0319 alter gene expression. DCDC2B (1p), the homolog of DCDC2, showed suggestive evidence for association to ADHD, but not RD. Previous association findings in NEDD4L (18q) could not be replicated.
No pleiotropic gene for RD and ADHD was identified. However, together with previous findings, this study supports that neuronal migration may be a common underlying deficit in both RD and ADHD.MAS
